From 85a0001b90efe59e52f89b62cda56771d79d0242 Mon Sep 17 00:00:00 2001 From: Taisuke Yamada Date: Thu, 7 Jun 2012 13:35:31 +0900 Subject: [PATCH] - Imported block-refresh (commit+shrink) patch from qemu-kvm custom branch. Signed-off-by: Taisuke Yamada diff --git a/block/vmdk.c b/block/vmdk.c index 18e9b4c..3241be6 100644 --- a/block/vmdk.c +++ b/block/vmdk.c @@ -1388,6 +1388,8 @@ static int vmdk_create(const char *filename, QEMUOptionParameter *options) total_size = options->value.n; } else if (!strcmp(options->name, BLOCK_OPT_BACKING_FILE)) { backing_file = options->value.s; + } else if (!strcmp(options->name, BLOCK_OPT_BACKING_FMT)) { + ; // ignore - VMDK is the only supported format, after all } else if (!strcmp(options->name, BLOCK_OPT_COMPAT6)) { flags |= options->value.n ? BLOCK_FLAG_COMPAT6 : 0; } else if (!strcmp(options->name, BLOCK_OPT_SUBFMT)) { @@ -1574,6 +1576,11 @@ static QEMUOptionParameter vmdk_create_options[] = { .help = "File name of a base image" }, { + .name = BLOCK_OPT_BACKING_FMT, + .type = OPT_STRING, + .help = "File format of a base image" + }, + { .name = BLOCK_OPT_COMPAT6, .type = OPT_FLAG, .help = "VMDK version 6 image" diff --git a/blockdev.c b/blockdev.c index 67895b2..e5df77a 100644 --- a/blockdev.c +++ b/blockdev.c @@ -832,6 +832,90 @@ exit: } +void qmp_block_refresh(const char *device, Error **errp) +{ + BlockDriverState *bs; + BlockDriver *drv; + int ret = 0; + int flags; + char curfile[1024], newfile[1024], oldfile[1024]; + pid_t pid = getpid(); + + bs = bdrv_find(device); + if (!bs) { + error_set(errp, QERR_DEVICE_NOT_FOUND, device); + return; + } + + // Check if this device is really in diff+backing file configuration + // Otherwise, there is no point in "refresh"ing. + if (!bs->backing_hd) { + return; // success-as-nop + } + + // Keep a copy of parameters needed after bdrv_close(bs). + drv = bs->drv; + flags = bs->open_flags; + snprintf(curfile, sizeof(curfile), "%s", bs->filename); + snprintf(newfile, sizeof(newfile), "%s.%d.new", bs->filename, pid); + ret = snprintf(oldfile, sizeof(oldfile), "%s.%d.old", bs->filename, pid); + + // Pathname too long + if (ret < 0 || ret >= sizeof(oldfile)) { + error_set(errp, QERR_BUFFER_OVERRUN); + return; + } + + // Quick sanity check to prevent unexpected overwrite. + if (access(newfile, F_OK) == 0 || access(oldfile, F_OK) == 0) { + error_set(errp, QERR_UNSUPPORTED); + return; + } + + // Commit all data back to backing file + ret = bdrv_commit(bs); + if (ret != 0) { + error_set(errp, QERR_IO_ERROR); + return; + } + + // Create new block image, with same backing file and flags + ret = bdrv_img_create(newfile, + bs->drv->format_name, + bs->backing_file, + bs->backing_hd->drv->format_name, + NULL, -1, bs->open_flags); + if (ret != 0) { + error_set(errp, QERR_OPEN_FILE_FAILED, newfile); + return; + } + + // Switch block image by close-rename-open + bdrv_close(bs); + if (rename(curfile, oldfile) != 0) goto error_rename_cur; + if (rename(newfile, curfile) != 0) goto error_rename_new; + if (bdrv_open(bs, curfile, flags, drv) != 0) goto error_reopen; + + // Successfully completed + unlink(oldfile); + return; + + // Upon failure, try to recover back to original state +error_reopen: + rename(curfile, newfile); +error_rename_new: + rename(oldfile, curfile); +error_rename_cur: + ret = bdrv_open(bs, curfile, flags, drv); + + if (ret != 0) { + error_set(errp, QERR_OPEN_FILE_FAILED, curfile); + } + else { + error_set(errp, QERR_UNDEFINED_ERROR); + } +} + static void eject_device(BlockDriverState *bs, int force, Error **errp) { if (bdrv_in_use(bs)) { diff --git a/hmp-commands.hx b/hmp-commands.hx index 18cb415..d096dc2 100644 --- a/hmp-commands.hx +++ b/hmp-commands.hx @@ -901,6 +901,20 @@ Snapshot device, using snapshot file as target if provided ETEXI { + .name = "block_refresh", + .args_type = "device:B", + .params = "device", + .help = "refresh (commit+regenerate) cow image of device.", + .mhandler.cmd = hmp_block_refresh, + }, + +STEXI +@item block_refresh +@findex block_refresh +Refresh cow image of device. +ETEXI + + { .name = "drive_add", .args_type = "pci_addr:s,opts:s", .params = "[[:]:]\n" diff --git a/hmp.c b/hmp.c index bb0952e..c3792fd 100644 --- a/hmp.c +++ b/hmp.c @@ -713,6 +713,15 @@ void hmp_snapshot_blkdev(Monitor *mon, const QDict *qdict) hmp_handle_error(mon, &errp); } +void hmp_block_refresh(Monitor *mon, const QDict *qdict) +{ + const char *device = qdict_get_str(qdict, "device"); + Error *errp = NULL; + + qmp_block_refresh(device, &errp); + hmp_handle_error(mon, &errp); +} + void hmp_migrate_cancel(Monitor *mon, const QDict *qdict) { qmp_migrate_cancel(NULL); diff --git a/hmp.h b/hmp.h index 443b812..f5f61b6 100644 --- a/hmp.h +++ b/hmp.h @@ -55,6 +55,7 @@ void hmp_set_password(Monitor *mon, const QDict *qdict); void hmp_expire_password(Monitor *mon, const QDict *qdict); void hmp_eject(Monitor *mon, const QDict *qdict); void hmp_change(Monitor *mon, const QDict *qdict); +void hmp_block_refresh(Monitor *mon, const QDict *qdict); void hmp_block_set_io_throttle(Monitor *mon, const QDict *qdict); void hmp_block_stream(Monitor *mon, const QDict *qdict); void hmp_block_job_set_speed(Monitor *mon, const QDict *qdict); diff --git a/qapi-schema.json b/qapi-schema.json index 2ca7195..05c6b34 100644 --- a/qapi-schema.json +++ b/qapi-schema.json @@ -1244,6 +1244,20 @@ '*mode': 'NewImageMode'} } ## +# @block-refresh +# +# Re-generates CoW image of a block device. For certain block formats, +# this shrinks snapshot image back to minimal size. +# +# @device: the name of the device to refresh the image. +# +# Returns: nothing on success +# If @device is not a valid block device, DeviceNotFound +## +{ 'command': 'block-refresh', + 'data': { 'device': 'str' } } + +## # @human-monitor-command: # # Execute a command on the human monitor and return the output.